375 lines
9.8 KiB
Plaintext
375 lines
9.8 KiB
Plaintext
// selfhost/cmd/wcc/cgenstmt.ww — split out of cgen.ww.
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//
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// cgstmt is a thin dispatcher over n.kind; each branch defers to a
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// per-kind helper: cgblock, cgreturn, cgexprstmt, cglet, cgif, cgfor,
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// cgmassign, cgbreak, cgcontinue.
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//
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// The expression generator (cgexpr) lives in cgenexpr.ww; the
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// foundation (types, emit primitives, collect* tables, FFI/module
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// maps) lives in cgen.ww.
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use os;
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use mem;
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use ast;
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use tok;
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use typ;
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use sym;
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use strconv;
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// ---- statement cgen --------------------------------------------------
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fn cgstmt(c: *cgen, n: *node) void = {
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if (n == nil) { return; };
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let k: i32 = n.kind;
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if (k == N_BLOCK) { cgblock(c, n); return; };
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if (k == N_RETURN) { cgreturn(c, n); return; };
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if (k == N_EXPRSTMT) { cgexprstmt(c, n); return; };
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if (k == N_LET) { cglet(c, n); return; };
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if (k == N_IF) { cgif(c, n); return; };
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if (k == N_FOR) { cgfor(c, n); return; };
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if (k == N_MASSIGN) { cgmassign(c, n); return; };
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if (k == N_BREAK) { cgbreak(c, n); return; };
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if (k == N_CONTINUE) { cgcontinue(c, n); return; };
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c.lastwasreturn = 0;
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};
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fn cgblock(c: *cgen, n: *node) void = {
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let s: *node = n.list;
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for (s != nil) {
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cgstmt(c, s);
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s = s.next;
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};
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return;
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};
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fn cgreturn(c: *cgen, n: *node) void = {
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let rhs: *node = n.lhs;
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if (rhs != nil) {
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// Tuple return `return a, b;` — pack as (AX=v0, DX=v1).
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// Matches C cgen: evaluate v1 first (PUSHQ), then v0
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// into AX, then POPQ DX. End state: AX = v0, DX = v1.
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if (rhs.kind == N_TUPLE) {
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let v: *node = rhs.list;
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if (v != nil) {
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let v2: *node = v.next;
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if (v2 != nil) {
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cgexpr(c, v2);
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emitline("\tPUSHQ\tAX\n");
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cgexpr(c, v);
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emitline("\tPOPQ\tDX\n");
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} else {
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cgexpr(c, v);
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};
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};
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emitline("\tMOVQ\tBP, SP\n");
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emitline("\tPOPQ\tBP\n");
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emitline("\tRET\n");
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c.lastwasreturn = 1;
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return;
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};
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// Tagged-union return: pack as (AX=tag, DX=value0, CX=value1).
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// For str variant, cgexpr leaves (AX=ptr, BX=len), so we
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// shuffle DX←AX (ptr) and CX←BX (len), then load tag.
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// For other variants, cgexpr leaves AX, shuffle DX←AX.
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if (istaggedtype(c.fnret)) {
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cgexpr(c, rhs);
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let idx: i32 = taggedvariantindex(c, c.fnret, rhs);
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if (nodeisstr(c, rhs)) {
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emitline("\tMOVQ\tBX, CX\n");
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emitline("\tMOVQ\tAX, DX\n");
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} else {
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emitline("\tMOVQ\tAX, DX\n");
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};
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emitline("\tMOVQ\t$");
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if (idx < 0) { idx = 0; };
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emitint(idx: i64);
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emitline(", AX\n");
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emitline("\tMOVQ\tBP, SP\n");
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emitline("\tPOPQ\tBP\n");
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emitline("\tRET\n");
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c.lastwasreturn = 1;
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return;
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};
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cgexpr(c, rhs);
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} else {
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// Bare `return;` in a void fn — zero AX so the caller
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// sees a deterministic value (matches C cgen, which
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// always falls through to `cgexpr_int(c, 0)`).
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emitline("\tMOVQ\t$0, AX\n");
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};
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// SysV: 16-byte aggregates (str, 2-tuple) return in (AX, DX).
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// cgexpr leaves str in (AX, BX); shuffle BX→DX.
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if (isstrtype(c, c.fnret)) {
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emitline("\tMOVQ\tBX, DX\n");
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};
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emitline("\tMOVQ\tBP, SP\n");
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emitline("\tPOPQ\tBP\n");
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emitline("\tRET\n");
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c.lastwasreturn = 1;
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return;
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};
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fn cgexprstmt(c: *cgen, n: *node) void = {
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if (n.lhs != nil) { cgexpr(c, n.lhs); };
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c.lastwasreturn = 0;
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return;
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};
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fn cglet(c: *cgen, n: *node) void = {
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let nm: str = n.str;
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let sz: i32 = slotsize(c, n.lhs);
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let off: i32 = localadd(c, nm, sz, n.lhs);
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if (n.rhs != nil) {
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let rhs: *node = n.rhs;
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// Tagged-union init: `let r: (T | E) = expr;`.
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// - If rhs is a CALL to a fn returning tagged-union,
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// the result is already in (AX=tag, DX=v0, CX=v1);
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// just spill all three.
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// - Otherwise rhs is a bare variant value: pack tag +
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// value(s).
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if (istaggedtype(n.lhs)) {
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let rhsreturnstagged: bool = false;
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if (rhs.kind == N_CALL) {
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let callee: *node = rhs.lhs;
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if (callee != nil) {
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let calleename: str;
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calleename.ptr = nil; calleename.len = 0;
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if (callee.kind == N_IDENT) { calleename = callee.str; };
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if (callee.kind == N_DOT) { calleename = callee.str; };
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if (calleename.len > 0) {
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let rt: *node = fnretlookup(c, calleename);
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if (istaggedtype(rt)) { rhsreturnstagged = true; };
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};
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};
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};
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cgexpr(c, rhs);
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if (rhsreturnstagged) {
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emitline("\tMOVQ\tAX, ");
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emitoff(off: i64);
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emitline("(BP)\n");
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emitline("\tMOVQ\tDX, ");
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emitoff((off + 8): i64);
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emitline("(BP)\n");
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emitline("\tMOVQ\tCX, ");
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emitoff((off + 16): i64);
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emitline("(BP)\n");
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c.lastwasreturn = 0;
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return;
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};
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let tagidx: i32 = taggedvariantindex(c, n.lhs, rhs);
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if (tagidx < 0) { tagidx = 0; };
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if (nodeisstr(c, rhs)) {
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emitline("\tMOVQ\tAX, ");
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emitoff((off + 8): i64);
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emitline("(BP)\n");
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emitline("\tMOVQ\tBX, ");
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emitoff((off + 16): i64);
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emitline("(BP)\n");
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} else {
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emitline("\tMOVQ\tAX, ");
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emitoff((off + 8): i64);
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emitline("(BP)\n");
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};
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emitline("\tMOVQ\t$");
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emitint(tagidx: i64);
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emitline(", ");
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emitoff(off: i64);
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emitline("(BP)\n");
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c.lastwasreturn = 0;
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return;
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};
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// Struct literal init: `let p: point = point{x=..., y=...};`.
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// For each field in the lit, evaluate its value and store at
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// the field's offset within the slot. Field-name → offset
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// from the struct registry.
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if (rhs.kind == N_STRUCTLIT) {
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let trefn: *node = rhs.lhs;
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let sname: str;
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sname.ptr = nil; sname.len = 0;
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if (trefn != nil) {
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if (trefn.kind == N_IDENT) { sname = trefn.str; }
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else { if (trefn.kind == N_TNAME) { sname = trefn.str; }; };
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};
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let si: *structinfo = structlookup(c, sname);
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if (si != nil) {
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let fieldnode: *node = rhs.list;
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for (fieldnode != nil) {
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if (fieldnode.kind == N_FIELD) {
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let fname: str = fieldnode.str;
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let fi: *fieldinfo = si.fields;
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for (fi != nil) {
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let fn_: str = fi.fname;
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if (streq(fn_, fname)) {
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cgexpr(c, fieldnode.lhs);
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let sop: str = fieldstoreop(fi);
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emitline("\t");
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emitline(sop);
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emitline("\tAX, ");
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emitoff((off + fi.foff): i64);
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emitline("(BP)\n");
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fi = nil;
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} else {
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fi = fi.finext;
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};
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};
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};
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fieldnode = fieldnode.next;
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};
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c.lastwasreturn = 0;
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return;
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};
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};
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cgexpr(c, rhs);
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emitline("\tMOVQ\tAX, ");
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emitoff(off: i64);
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emitline("(BP)\n");
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// str init: cgexpr also leaves len in BX; store both.
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if (sz == 16) {
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emitline("\tMOVQ\tBX, ");
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emitoff((off + 8): i64);
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emitline("(BP)\n");
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};
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// slice init: ptr/len/cap in AX/BX/CX.
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if (sz == 24) {
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emitline("\tMOVQ\tBX, ");
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emitoff((off + 8): i64);
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emitline("(BP)\n");
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emitline("\tMOVQ\tCX, ");
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emitoff((off + 16): i64);
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emitline("(BP)\n");
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};
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} else {
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// Bare `let x: T;` with no initializer. C cgen
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// (cmd/w6c/cgen.c:2181-2183) zero-inits only when
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// the underlying type's natural size is 8 — pointers,
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// i64/u64, function pointers, ints. Structs/arrays/
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// slices/strings/tagged/tuples are left for per-field
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// writes. ww's slotsize pads struct slots up to 8,
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// so we can't just check sz == 8: walk the type AST
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// directly to make the same call.
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if (typeis8byteprimitive(c, n.lhs)) {
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emitline("\tMOVQ\t$0, ");
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emitoff(off: i64);
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emitline("(BP)\n");
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};
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};
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c.lastwasreturn = 0;
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return;
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};
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fn cgif(c: *cgen, n: *node) void = {
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let els: str = mklabel(c, "else");
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let endl: str = mklabel(c, "end");
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cgexpr(c, n.cond);
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emitline("\tCMPQ\t$0, AX\n");
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emitline("\tJE\t");
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if (n.els != nil) { emitline(els); }
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else { emitline(endl); };
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emitline("\n");
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if (n.body != nil) { cgstmt(c, n.body); };
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if (n.els != nil) {
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emitline("\tJMP\t"); emitline(endl); emitline("\n");
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emitlabel(els);
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cgstmt(c, n.els);
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};
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emitlabel(endl);
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c.lastwasreturn = 0;
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return;
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};
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fn cgfor(c: *cgen, n: *node) void = {
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// Match C cgen's label scheme: <fn>_loop_N for the top,
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// <fn>_endloop_N for the post-body merge. No separate cont
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// label when there's no post-expression.
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let topl: str = mklabel(c, "loop");
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let endl: str = mklabel(c, "endloop");
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if (n.lhs != nil) { cgstmt(c, n.lhs); };
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emitlabel(topl);
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if (n.cond != nil) {
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cgexpr(c, n.cond);
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emitline("\tCMPQ\t$0, AX\n");
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emitline("\tJE\t"); emitline(endl); emitline("\n");
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};
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c.loopendbuf[c.looptop] = endl;
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c.loopcontbuf[c.looptop] = topl;
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c.looptop += 1;
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if (n.body != nil) { cgstmt(c, n.body); };
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c.looptop -= 1;
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if (n.rhs != nil) { cgexpr(c, n.rhs); };
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emitline("\tJMP\t"); emitline(topl); emitline("\n");
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emitlabel(endl);
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c.lastwasreturn = 0;
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return;
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};
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// Tuple-destructure assign: `a, b = call();`. The call's tuple
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// return lands in (AX, DX); push DX to free it, store AX into
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// the first lvalue, then pop DX into the second. Mirrors
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// cmd/w6c/cgen.c:2424-2440. Lvalues beyond two are dropped (same
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// as C — no fixture uses >2 today).
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fn cgmassign(c: *cgen, n: *node) void = {
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if (n.rhs != nil) { cgexpr(c, n.rhs); };
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emitline("\tPUSHQ\tDX\n");
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let l0: *node = n.list;
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let l1: *node = nil;
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if (l0 != nil) { l1 = l0.next; };
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if (l0 != nil) {
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if (l0.kind == N_IDENT) {
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let off: i32 = localfind(c, l0.str);
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if (off != 0) {
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emitline("\tMOVQ\tAX, ");
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emitoff(off: i64);
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emitline("(BP)\n");
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};
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};
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};
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emitline("\tPOPQ\tDX\n");
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if (l1 != nil) {
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if (l1.kind == N_IDENT) {
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let off: i32 = localfind(c, l1.str);
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if (off != 0) {
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emitline("\tMOVQ\tDX, ");
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emitoff(off: i64);
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emitline("(BP)\n");
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};
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};
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};
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c.lastwasreturn = 0;
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return;
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};
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fn cgbreak(c: *cgen, n: *node) void = {
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if (c.looptop > 0) {
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let lbl: str = c.loopendbuf[c.looptop - 1];
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emitline("\tJMP\t"); emitline(lbl); emitline("\n");
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};
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c.lastwasreturn = 0;
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return;
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};
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fn cgcontinue(c: *cgen, n: *node) void = {
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if (c.looptop > 0) {
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let lbl: str = c.loopcontbuf[c.looptop - 1];
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emitline("\tJMP\t"); emitline(lbl); emitline("\n");
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};
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c.lastwasreturn = 0;
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return;
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};
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